LAUSR

BACKGROUND High-level spinal cord injury (SCI) results in profound spinal and supraspinal deficits, leading to substantial ventilatory limitation during whole-body hybrid functional electrical stimulation (FES)-rowing, a form of exercise that markedly increases the active muscle mass via electrically-induced leg contractions. We tested the effect of non-invasive ventilation (NIV) on ventilatory and aerobic capacities during in SCI. METHODS Nineteen patients with SCI (C4-T8) were enrolled in a blinded randomized cross-over study. All patients were familiar with FES-rowing and had plateaued in their training-related increases in aerobic capacity. Patients performed 2 FES-rowing peak exercise tests with NIV or Sham. RESULTS NIV increased exercise tidal volume (peak: 1.50 ± 0.31 vs.1.36 ± 0.34 L, p < 0.05) and reduced breathing frequency (peak: 35 ± 7 vs. 38 ± 6 bpm, p < 0.05) compared to sham, leading to no change in alveolar ventilation (VA) but a trend to increased oxygen uptake efficiency (p = 0.06). In those who reached VO2peak criteria (n = 13), NIV failed to significantly increase VO2peak (1.73 ± 0.66 vs.1.78 ± 0.59 L/min); however, the range of responses revealed a correlation between changes in VApeak and VO2peak (r = 0.89, p < 0.05). Furthermore, those with higher level injuries and shorter time since injury demonstrated the greatest increases in VO2peak. CONCLUSION Acute NIV can successfully improve ventilatory efficiency during FES exercise in SCI but may not improve VO2peak in all patients. Those who benefit most appear to be patients with cervical SCI within a shorter time since injury.